Jetpack
Comments are a great way to create a community around your site. They’re easy to use, and they require no technical expertise JetPack makes it a bit easier process to create by doing a few improvements on your site.
Jetpack Comments is a new comment form for your WordPress blog. It makes your comment form a bit more modern, adding an interface and making it easier to log into your site with one of your existing social media accounts.
wpDiscuz
wpDiscuz transforms your discussion experience on your website. It offers several features that will make your posts more engaging for your visitors. This plugin is designed to allow you to use different layouts for different post types and pages using the custom form builder setting.
You can also create a rating field in the comment form to let users rate posts while writing their comments. It is trusted by more than 9 thousand businesses and is considered one of the best comment plugins available.
Disqus
With machine learning and comment history, we automatically detect and remove spam before it ever gets to your site. It also helps publishers keep their audience engaged and help them stay connected.
Get the right people to contribute to your site, so that your article can become more useful and trustworthy in the eyes of the search engine and other readers and you don't have to work hard as a tool like Disqus can do that for you.
Postmatic
Postmatic has created a service that makes commenting easier than ever. By filling out a simple online comment form and continuing the conversation through email, Postmatic has made it much more fun for you to interact with your audience.
With this plugin, you never have to check your articles again to see if somebody commented or not. All comments are sent to your inbox, so you don't miss out on any of them as you can always pick up the phone and reply to them easily.
Thrive Comments
Thrive Comments is well known because they understood the power of having a direct connection with their audience. Thrive's unique upvote/downvote feature really adds to the experience and makes it easy for users to exactly what they are looking for.
It is an advanced comment moderation dashboard designed to help you quickly sort your comments that include multiple sorting options, including only those comments made only from your posts, comments still requiring a response, and comments on one page or post.